Such an image processing device as a CRT (Cathod-Ray Tube), an LCD (Liquid Cristal Display), a Projector, a wearable device, and the like processes an image using a fixed focal depth, i.e., a fixed focus, irrespective of a user.
Yet, when eye sight is different from each other according to a user and there are various conditions such as surroundings, if a user watches an image through an image processing device processing an image with a legacy fixed focus, the user may feel inconvenience due to an out of focus or it may be difficult for the user to properly feel an effect of a processed image. And, in case of the aforementioned case, the user may feel tired in a few minutes after starting to watch an image.